Why don't you try using this IRS interactive tool (click on link below). It will take you through a series of questions and help you determine if you can claim this person as a dependent. Hope this helps.
This response should not be considered legal advice. No attorney-client relationship is formed by this response, which reflects only the opinion of the author. The response should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question and could change if additional facts were made available.